Orbit raising manoevers completed with fifth Apogee Motor Firing (AMF) on July 06, 2013 at 16:57 hrs (IST) and performance is normal.Satellite is in Geo-Synchronous Orbit (GSO) with 27 deg inclination at 44 deg E longitude.Present orbital parameters are : apogee 35870 km, perigee 35484 km and orbital period is 23h 50m.All the spacecraft subsystem are evaluated and functioning normal.
Did the satellite start broadcasting navigation signals? Have the signals been received?
In the NavIC, a constellation of seven satellites, one of the three crucial rubidium timekeepers on IRNSS-1A spacecraft failed six months ago. The other two followed subsequently.
A. S. Kiran Kumar, Chairman of the Indian Space Research Organisation, confirmed the glitch in the clocks but clarified that the satellite was otherwise all right, and the rest of the satellites were performing its core function of providing accurate position, navigation and time. However, without its clocks, the IRNSS-1A “will give a coarse value. It will not be used for computation. Messages from it will still be used.”
“There are some anomalies in the atomic clock system on board. We are trying to restart it. Right now we are working out a mechanism for operating it,” he told The Hindu.“The problem is only with the clock system of one spacecraft. The signals are all coming, we are getting the messages, everything else is working and being used, except the stability portion which is linked to the clock,” he said. A minimum of four working satellites was sufficient to realise the full use of the navigation system”.
NavIC has 21 atomic clocks on seven spacecraft. “How would the other clocks fare? Would ISRO reconsider the supplier of its atomic clocks? Such questions are not easy to answer. Generally any [space] hardware is an issue. We have to find ways of going around it,” he said.
The troubled IRNSS-1A spacecraft was put in space in July 2013 and has an expected life span of 10 years.
